[Octave-bug-tracker] [bug #60924] DNAUPD did not find any eigenvalues to sufficient accuracy

[Rik]

Follow-up Comment #9, bug #60924 (project octave):

I just answered my own question.  I changed the code to


opts.isreal = true;
opts.maxit = 500;


and now it passes every time.

Similarly, making this change


opts.isreal = true;
opts.tol = 1000*eps ();


allows the code to pass every time.

I changed the level of debug output using


opts.disp = 2;
opts.maxit = 500;


When I run I see that the required number of iterations is usually around 325,
although I still get very occasional failures where the iteration count
reaches 500.

I think the error message just needs to be re-worked to suggest that users
adjust some of the parameters in order to have a better shot at convergence.

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